Method for operating modulated burners actuated by an emulsion

ABSTRACT

A method for operating modulated burners actuated by an emulsion and using a pre-stream exclusively formed of fuel before the reignition of the burner 1, said method comprising: ESTABLISHING THE RETURN OF SAID PRE-STREAM GENERATED BY A HIGH PRESSURE PUMP, THROUGH THE MEDIUM OF A MODULATED REGULATOR 5 AND OF A FIRST ELECTRO-VALVE 6; ESTABLISHING A FLOW OF LIQUID FUEL AND WATER EMULSION TO THE BURNER, BY OPENING A SECOND ELECTRO-VALVE 7; INTERRUPTING SAID PRE-STREAM BY CLOSING SAID FIRST ELECTRO-VALVE 6, AND IGNITING THE BURNER 1 BEFORE IT HAS BEEN REACHED BY THE EMULSION.

United States Patent 11 1 1111 3,837,784 Delatronchette 1 Sept. 24, 1974 METHOD FOR OPERATING MODULATED 3,383,049 5/1968 Guerin 239 400 BURNERS ACTUATED Y AN E S O 3,533,717 10/1970 Guerin 431/182 3,741,712 6/1973 Delatronchette 431/4 X Inventor: Claude Delatmnchette, Cachan, 3,766,942 10/1973 Delatronchette et a1. 431/4 x France Primar Examiner-William F. ODea A Elf- P F Y [73] sslgnee Unlon ans rdnce Assistant Examiner-Wflltam C. Anderson 1 1 Filed: y 1 1973 Attorney, Agent, or Firm-Cameron, Kerkam, Sutton, 2 Appl No: 359 71 Stowell & SIOWEll 30 F A P D t [57] ABSTRACT orelgn pp y a a A method for operating modulated burners actuated May 16, 1972 France 72.17500 by an emulsion and using a pre stream exclusively 52 us. (:1. 4131/ 1, 431 /29 fo-rmed of fuel befQr? 1 re'ignifion of the burner said method comprlslng. [5 Illlt. establishing the return of said pre stream generated [58] Field of Search 431/4, 6, 23, 32, 121, by a high pressure pump, through the medium of 431/29 239/8 110/75 a modulated regulator 5 and of a first electro-valve 6; [56] References cued establishing a flow of liquid fuel and water emulsion UNITED STATES PATENTS to the burner, by opening a second electro-valve 2,033,010 3/1936 Russell 431/4 7; 2,104,311 1/1938 Russell interrupting said pre-stream by closing said first 2,702,590 2/1955 Stillman 431/9 electro-valve 6, and igniting the burner 1 before it 2,818,1 10 12/1957 Rulseh 431/29 X h been reached by h emulsion 3,212,555 10/1965 Schuss et a1. 431/29 X 3,358,735 12/1967 Luft 431/29 4 Claims, 1 Drawing Figure ELECTRO- VALVE 1.g\ 14 15 :WW 9 12322- METHOD FOR OPERATING MODULATED BURNERS ACTUATED BY AN EMULSION The present invention relates to a method for operating modulated burners actuated by an emulsion of light or heavy liquid fuel, such as used for heating furnaces, boilers or similar devices.

It is known, from methods of the prior art, that, once such a burner has been stopped, it is quite uneasy to cause it to start again with the liquid fuel and water emulsion and under normal working conditions.

By way of improvement, another known method provides sending back the emulsion to the fuel tank, once the burner has been stopped, and eliminating any risk of corrosion or decantation in the burner when the stoppage of heating is protracted.

According to the latter method, the amount of emulsion contained in the conduits and burners is entirely spent until extinction. Before re-igniting the burner; a pre-steam exclusively formed of fuel is admitted into the burner injector, and, after a certain period of time the water circuit is opened in order to provide a gapless feed of liquid fuel and water emulsion; the interruption of the pre-stream of fuel coincides with the ignition of the burner which consumes, first the liquid fuel above, then the emulsion.

Some heating devices are provided with only one variable rate burner fed in a closed circuit. In such instances, the closed-circuit return of the emulsion to the fuel tank, such as practised in the above-mentioned methods, is not suitable for the return of the liquid fuel along during the pre-stream period and of the emulsion during normal operation.

The present invention aims, in particular, at obviating the above-mentioned drawbacks of known methods.

More specifically, the present invention relates to a method for operating modulated burners actuated by an emulsion and using a pre-stream exclusively formed of fuel before the re-ignition of the burner following an interruption of the normal heating, the amount of liquid fuel and water emulsion remaining in the conduits having been fully spent during the previous burner extinction, the interruption of said pre-stream coinciding with the ignition of the burner which consumes, first the liquid fuel above, then, after a given period of time, the liquid fuel and water emulsions provided by a mixer which is fed with liquid fuel, on the one hand, and with water, on the other hand, said method comprising:

establishing the return of said pre-stream of fuel generated by a high-pressure pump and which flows through the burner, through the medium of a modulating regulator and of a first electro-valve 6 mounted on the return conduit to the fuel tank; establishing a flow of liquid fuel and water emulsion to the burner, by opening a second electro-valve 7 which communicates the exit of the regulator with another inlet of the mixer, the latter being fed with water by means of a third electro-valve l; interrupting said pre-stream of fuel by closing said first electro-valve 6, after a given period during which said pre-stream and the flow of emulsion overlapped; and, igniting the burner during the overlapping period, be-

fore the liquid fuel and water emulsion has reached said burner. I

The above pre-stream is intended to eliminate the liquid fuel which cooled down in the burner conduits during the periods of extinction. By opening the second electro-valve before the pre-stream has been caused to stop, it is possible to fill the conduits between the burner and the mixer with emulsion, and to leave but a small amount constituted by liquid fuel exclusively in the burner nozzles, with a view to providing a perfect ignition.

According to another feature of the present invention, it is proceeded with a pre-sweeping of the burner before the extinction thereof, by closing the third electro-valve 15, and the burner is caused to blow out, once the emulsion has been entirely spent, by closing the second electro-valve 7.

According to another feature, a programming-unit is used for controlling said electro-valves separately.

According to still another feature of the invention, the information provided by a thermostat of the boiler are used for controlling the modulating regulator.

Other features of the present invention will appear from the following description, given merely by way of example.

In the sole FIGURE, numeral 1 designates a modulating burner, fed by a low-pressure feed circuit 9 of known type, which comprises a pump 10 adapted to draw liquid fuel from a tank 4. Said liquid fuel is sucked by a high-pressure pump 3 through a re-heater 8 a oneway valve 11 and mixer 2, and it is directed to burner ll, through a conduit 1a.

The return of the liquid fuel from burner 1 is carried out, after passing through a modulating regulator 5, along either of the following two circuits; one of these circuits, for the direct return of the pre-stream goes to low-pressure feed circuit 9, through normally open electro-valve 6 and conduit 19.

Electro-valve 7 is normally kept closed. The other of said two circuits, for the return of the normal flow of the liquid fuel and water emulsion to burner 1, goes through electro-valve 7 which is open (electro-valve 6 being closed), mixer 2 and conduit 1a.

The method according to the invention is carried out as follows:

burner l was emptied (pre-sweeping) of its liquid fuel and water emulsion during a previous extinction of the burner (third step).

In the first step of the method, corresponding to a pre-stream formed of liquid fuel exclusively, said fuel flows in succession through pump 10, re-heater 8, oneway valve 11, mixer 2, pump 3, conduit la, burner 1,

' conduit 1b, regulator 5, electro-valve 6, conduit 19 and low pressure feed circuit 10. In the course of said first operating step, electro-valves 7 and 15 are closed, so that cooled-down fuel is eliminated throughout the various conduits.

The second operating step corresponds to the normal flow of liquid fuel and water.

That second step overlaps the first one for a few seconds. It starts with the opening of electro-valve 15 of the water circuit, in order to obtain an emulsion in mixer 2. The first operating step is brought to a stop by the closing of electro-valve 6 and the opening of electro-valve 7.

The burner ignition occurs during the overlapping period the two steps, with a view to burning a very small amount formed of liquid fuel exclusively (perfect ignition), immediately followed by the liquid fuel and water emulsion.

Regulator 5 modulates the emulsion amount in burner 1 according to the boiler temperature indications.

The durations of the pre-stream (first step) and of the overlapping period (second step) can be programmated by means of devices known per se, which in fact are not within the scope of the present invention.

The third operating step corresponds to the extinction of burner 1; said third step can be controlled either by a thermostat or by regulator 5. It is started by the closing of electro-valve and lasts until all the emulsion contained in burner 1 has been spent.

With a view to repeating the first operating step, electro-valve 7 is caused to close and electro-valve 6 to open.

The above disclosed method according to the invention can be applied to all cases dealing with the feeding and modulating burners using liquid fuel.

What is claimed is:

l. A method for operating modulated burners actuated by an emulsion and using a pre-stream exclusively formed of fuel before the re-ignition of the burner following an interruption of the normal heating, the amount of liquid fuel and water emulsion remaining in the conduits having been fully spent during the previous burner extinction, the interruption of said prestream coinciding with the ignition of the burner which consumes, first the liquid fuel alone, then after a given period of time, the liquid fuel and water emulsion provided by a mixer which is fed with liquid fuel, on the one hand, and with water. on the other hand, said method comprising:

establishing the return of said prestream of fuel generated by a high-pressure pump and which flows through the burner, through the medium of a modulating regulator and of a first electro-valve mounted on the return conduit to the fuel tank;

establishing a flow of liquid fuel and water emulsion to the burner, by opening a second electro-valve which communicates the exit of the regulator with another inlet of the mixer, the latter being fed with water by means of a third electro-valve;

interrupting said pre-stream of fuel by closing said first electro-valve, after a given period during which said pre-stream and the flow of emulsion overlapped; and,

igniting the burner during the overlapping period, be-

fore the liquid fuel and water emulsion has reached said burner.

2. A method according to claim 1, wherein it is proceeded with a pre-sweeping of the burner before the extinction thereof, by closing the third electro-valve, and the burner is caused to blow out, once the emulsion has been entirely spent, by closing the second electrovalve.

3. A method acording to claim 1, wherein a programming-unit is used for controlling said electro-valves separately.

4. A method according to claim 1, wherein the information provided by a thermostat of the boiler are used for controlling the modulating regulator. 

1. A method for operating modulated burners actuated by an emulsion and using a pre-stream exclusively formed of fuel before the re-ignition of the burner following an interruption of the normal heating, the amount of liquid fuel and water emulsion remaining in the conduits having been fully spent during the previous burner extinction, the interruption of said pre-stream coinciding with the ignition of the burner which consumes, first the liquid fuel alone, then after a given period of time, the liquid fuel and water emulsion provided by a mixer which is fed with liquid fuel, on the one hand, and with water, on the other hand, said method comprising: establishing the return of said pre-stream of fuel generated by a high-pressure pump and which flows through the burner, through the medium of a modulating regulator and of a first electro-valve mounted on the return conduit to the fuel tank; establishing a flow of liquid fuel and water emulsion to the burner, by opening a second electro-valve which communicates the exit of the regulator with another inlet of the mixer, the latter being fed with water by means of a third electro-valve; interrupting said pre-stream of fuel by closing said first electro-valve, after a given period during which said prestream and the flow of emulsion overlapped; and, igniting the burner during the overlapping period, before the liquid fuel and water emulsion has reached said burner.
 2. A method according to claim 1, wherein it is proceeded with a pre-sweeping of the burner before the extinction thereof, by closing the third electro-valve, and the burner is caused to blow out, once the emulsion has been entirely spent, by closing the second electro-valve.
 3. A method acording to claim 1, wherein a programming-unit is used for controlling said electro-valves separately.
 4. A method according to claim 1, wherein the information provided by a thermostat of the boiler are used for controlling the modulating regulator. 